1. Field of the Invention
The invention relates to a multi-function printer, and in particular, a multi-function printer comprising a document feeding device for handling and reverting double-sided document sheets to an original sequence.
2. Description of the Related Art
As shown in FIG. 1, a conventional double-sided document feeding device (TW 095136895) is provided. The double-sided document feeding device comprises a housing unit 1 and a switching unit 2. The housing unit 1 comprises a delivery passage 101, a flipping passage 102 connected to the delivery passage 101 and a return passage 103 on a side of the delivery passage 101 and the flipping passage. The switching unit 2, pivotally disposed in the return passage 103, comprises a first switching member 201, a second switching member 202 connected to a side of the first switching member 201 and a guiding passage 203 between the first and second switching members 201, 202. When the switching unit 2 is in a first position, the first switching member 201 is mounted to allow communication between the delivery passage 101 and the return passage 103, and a first surface of the document sheet is therefore scanned. When the switching unit 2 is in a second position, the flipping passage 102 and the guiding passage 203 are communicated to flip the document sheet over, and a second surface of the document sheet is therefore scanned. When the switching unit 2 is in a third position, the delivery passage 101 and the guiding passage 203 are disconnected in order to send out the document through the flipping passage 102 and the delivery passage 101, after the first surface and the second surface of the document have been scanned.
The double-sided document feeding device utilizes the switching of the switching unit 2 to flip and scan the double-sided document sheets and revert the document sheets to an original sequence. However, the flipping passage 102 and the delivery passage 101 are required in order to revert the document sheet to an original sequence. As a result, the previous document sheet of the document must be completely ejected from the delivery passage 1, and the switching unit 2 must return from the third position to the first position, and the next document sheet of the document is then be able to be scanned. Thus, it slows down the scanning speed of the conventional double-sided document feeding device.